A vehicle-mounted electronic control device, such as a general motor-driving inverter device, has a structure where an electronic component unit equipped with a semiconductor switching element, a control circuit, etc. is received in a protective space (a space provided with waterproofing, etc.) inside of a housing prepared by assembling and joining a plurality of housing members (for example, Patent Publications 1 and 2).
As a specific example of the electronic control device, there is known a structure in which two housing members (housing members, etc. to be opposingly arranged and joined) to be joined with each other are fastened by a fastening means (screw, etc.) for joining in a condition an elastic packing (rubber packing, etc.) is interposed between their joining surfaces to seal the joining surfaces (for example, Patent Publication 3). Furthermore, there is also known a structure in which a sealing groove is formed on the joining surface of one housing member, and they are fastened together by a fastening means for joining in a condition where an elastic packing is fitted into the sealing groove (for example, Patent Publications 4 and 5). Besides, instead of applying an elastic packing, it is possible to think of a structure in which they are joined in a condition that the sealing groove is filled with a sealing material (a sealing material with fluidity and adhesion, such as liquid gasket), and then the joining surfaces are sealed by hardening the sealing material.